1. Field of the Invention
The present invention relates to a liquid jet head that jets liquid droplets from nozzles by displacement of piezoelectric elements, and a liquid jet apparatus, and in particular, to an ink jet type recording head that jets ink droplets as liquid droplets, and an ink jet type recording apparatus.
2. Invention of Related Art
An ink jet type recording head, which is an example of a liquid jet head jetting liquid droplets, includes a flow channel forming plate having pressure generation chambers, and piezoelectric elements provided on one surface of the flow channel forming plate, each of the piezoelectric elements having a lower electrode, a piezoelectric material layer, and an upper electrode. Pressure is given into the pressure generation chambers by displacement of the piezoelectric elements, and ink droplets are jetted from nozzles. The piezoelectric elements, which are used in such an ink jet type recording head, are liable to be broken due to external environment, such as humidity or the like. In order to solve this problem, for example, the outer circumferential surface of the piezoelectric material layer is covered with the upper electrode (for example, see JP-A-2005-88441).
As described in Patent Document 1, if the piezoelectric material layer is covered with the upper electrode, the piezoelectric material layer can be prevented from being broken due to humidity. In this case, however, the upper electrode and the lower electrode at the end surface of the piezoelectric material layer become very close to each other. For this reason, insulation breakdown may occur between both electrodes, and the piezoelectric element may be broken.